The mounting of a plurality of separate rotating members on a common shaft is very well known and has a number of diverse applications. In a typical application, each rotating member will carry its own separate bearing system, in order to be independently rotatable. A common problem in all of such arrangements is the possible friction between adjacent members, particularly when rotated at different speeds. Such problem is not solved by the use of spacers between adjacent members or stops or shoulders on the shaft, due to the friction between the member and its spacer, stop or shoulder. Friction between adjacent rotatable members is especially problematic in arrangements wherein the rotatable members are slidably mounted on the shaft, such that the members become loaded against each other.
In my U.S. Pat. No. 3,528,645, there is described a bearing or pulley block utilizing ball bearings on both sides of the sheave. The balls provide bearing support not only for the sheave, but also bear against the side plates of the block, thereby greatly reducing friction and binding.